There has so far been marketed a disk player device dedicated to reproduction, such as a CD player designed to reproduce a so-called compact disk (CD), which is an optical disk on which audio signals such as voice or musical sounds are recorded in digitized form. While the conventional CD player is dedicated to reproduction, attempts have been made to develop a disk system which, through the use of a magneto-optical disk formed by a photo-magnetic recording medium allowing rewriting of information, is adapted for both recording and reproduction and able to maintain superior compatibility with respect to the compact disk.
As shown diagrammatically in FIG. 1, the recordable disk 1 employed in the above disk system is formed with spirally extending pregrooves 2 having a depth equal to .lambda./8, wherein .lambda. indicates the wavelength of the laser beam used for information recording. On a land 3 between the adjacent pregrooves 2, a prerecorded region 4 in which patterns of projections and recesses formed by pits each .lambda./4 deep are previously recorded and a data recording region 5 in which magneto-optical recording is performed, are formed alternately in the circumferential direction, each at an equal pitch. A lead-in region 7 is provided at the inner periphery of the program region 6 in which the performance information is recorded. In this lead-in region, there is recorded TOC or table of contents information indicating the record contents of the program region 6. In the prerecorded region 4 of the recordable disk 1, there are recorded 24 bits of sync signals and 14 bits or 1 symbol of subcode as patterns of projections and recesses formed in advance by a molding operation as indicated in FIG. 3. These subcodes represent the absolute time information or absolute addresses from the start position of the program region 6. The above 24 bit sync signals and 14 bit subcodes are a part of the 588 channel bit data making up one frame of the data format, as shown in FIG. 2, standardized for the compact disk (CD), and including, in addition to the above sync signals and subcodes, 14.times.32 bits (32 symbols) of the data such as the performance information and parities and margin bits, each of 3 bits, provided between adjacent symbols.
In a disk system employing the above described recordable disk 1, disk rotation control etc. is performed at a constant linear velocity (CLV), utilizing the aforementioned absolute addresses reproduced from the prerecorded region 4 of the recordable disk 1, so that the information is recorded in the data format standardized for the compact disk (CD).
It will be noted that, in the disk system employing the recordable disk, such as the magneto-optical disk formed by the magneto-optical recording medium, when a track jump takes place, that is, when the scanning beam from an optical head jumps from a presently recorded track or current track to another track due to vibrations caused during the recording operation or disk defects, the recorded performance information may be discontinuous or become discrete as a function of the amount of such track jump, such that the performance may be interrupted depending on the amount of the track jump during reproduction and, in the worst case, a performance information is over-written on the previously recorded track to destroy the previously recorded performance information.
It is therefore an object of the present invention to provide a disk recording apparatus of a novel construction in which a track jump is detected during the recording operation and the mistaken recording of the information on the tracks other than the target track is avoided.